OSHA RECOMENDED HEAT WORK SCHEDULE

There are many options for the oppressive summer time heat, from, ignore it and it will go away, to Don’t work in the summertime. Since these should not be the solution to the problem here are some solutions you may think are appropriate for your type of work….

OSHA RECOMMENDED HEAT WORK SCHEDULE from their website

OSHA’s Campaign to Prevent Heat Illness in Outdoor Workers – Protective Measures to Take at Each Rick Level – About Work/Rest Schedules

About Work/Rest Schedules

Choosing Shaded Rest Areas:

When an air conditioned space is not available, choose or create rest areas with as many of the following beneficial characteristics as possible:

  • In full (complete) shade.
  • Where surfaces are not warm from earlier sun (e.g., north-facing wall).
  • Opened to cooling breezes, but protect workers if breezes feel uncomfortably hot, which can increase risk of heat illness.
  • Free of other hazards (e.g., moving traffic, excessive noise, falling objects).
  • With sufficient space for the number of workers needing rest breaks at one time.
  • Near a supply of cool drinking water.
  • Equipped for workers to do productive light work while their bodies cool.

Rather than being exposed to heat for extended periods of time during the course of a job, workers should, wherever possible, be permitted to distribute the workload evenly over the day and incorporate work/rest cycles. Work/rest cycles give the body an opportunity to get rid of excess heat, slow down the production of internal body heat, slow down the heart rate, and provide greater blood flow to the skin.

For the best protection from heat-related illness, workers should spend the rest periods of the cycle in a cool place, for example in a lightly air conditioned room, trailer or vehicle, or if one is not available, then in full shade.

Rest periods do not necessarily mean that the workers are on break; these can be productive times. During the rest periods, workers may continue to perform mild or light work, such as completing paperwork, sorting small parts, attending a meeting, or receiving training (e.g., instructions for upcoming work, or a tailgate safety talk).

Have a knowledgeable person at the worksite that is well-informed about heat-related illness and able to modify work activities and the work/rest schedule as needed. When evaluating an appropriate work/rest schedule:

  • Shorten work periods and increase rest periods:
    • As temperature rises
    • As humidity increases
    • When sun gets stronger
    • When there is no air movement
    • When protective clothing or gear is worn
    • For heavier work
  • Assign new and un-acclimatized workers lighter work and longer rest periods. Monitor these workers more closely.

The figures and tables below are examples of general guidelines for setting work/rest schedules. When possible, more frequent shorter periods of exposure to heat are better than fewer longer exposures. This means that the work/rest schedules are often based on 1-hour cycles and might call for a rest period of 15 minutes every hour during hot weather, but 45 minutes per hour when temperature and humidity are extreme. Individual requirements may vary greatly. The work/rest schedules in these tables do not guarantee protection against heat-related illness and should not be used as a substitute for good judgment or experience. The tables generally apply to healthy, acclimatized adults under the age of 40.

Setting appropriate work rest schedules is critical for protecting workers during outdoor work. Often it requires the assistance of a trained safety and health profession. In addition to the methods provided as examples below, OSHA provides free and confidential advice to services small and medium-sized businesses in all states across the country. Contact OSHA’s On-site Consultation Program for assistance in developing your heat-related illness preventions plan and work/rest schedules that are appropriate for your worksite. For more information or for additional compliance assistance contact OSHA at 1-800-321-OSHA (6742).

Methods for Developing Work/Rest Schedules

 

The US Army Work/Rest/Water Consumption table used for setting work/rest schedules during field operations. The hydration and work/rest schedule assume an average sized, heat acclimated soldier wearing battle dress uniforms (BDU). Factors such as lack of acclimitization, poor fitness, and cumulative inadequate hydration and may increase the risk of heat-related illness and should be taken into account when using the schedules in Figure 1. This is one method for determining work/rest schedules using an alternate to the Heat Index called the Wet-Bulb Globe Temperature (WBGT). The WBGT is obtained using specialized equipment (a wet-bulb globe temperature meter, also known as a WBGT meter). The meter provides a heat reading based in part on factors similar to those NOAA uses to determine the heat index, but the WBGT reading also considers solar load (radiant heat, from sunshine) as well as how quickly moisture evaporates. WBGT meters are readily available from commercial sources of environmental monitoring and technical instruments. Several hand-held models cost less than $200 (in 2011).

FIGURE 1: US. ARMY APPROACH FOR SETTING WORK/REST SCHEDULES

[Text Version]

Table 1 presents an approach for setting work/rest schedules for workers wearing normal clothing drawn from the US EPA/OSHA joint publication

Tables 1 and 2 use an adjusted temperature calculation to approximate the Wet Bulb Globe Temperature (WBGT). These tables are for use where instruments which measure WBGT are unavailable. Some of the work/rest times in Table 1 for hot/dry conditions may be conservative, due to approximation of WBGT. While Tables 1 and 2 allow 13° for the full heating effect of the sun, the effect of solar heat can be greater under some conditions. Table 1 is based in part on there being perceptible air movement. Where there is little or no air movement, Table 1 is not appropriate.

*Note: Adjust the temperature reading as follows before going to the temperature column in the table:

Full sun (no clouds)

add 13°

Partly cloudy/overcast

add 7°

No shadows visible/work is in the shade or at night

no adjustment

For relative humidity of:  

10%

subtract 8°

20%

subtract 4°

30%

no adjustment

40%

add 3°

50%

add 6°

60%

add 9°

Note there is no entry for humidity’s above 60%  as AGIH makes its recommendations with regard to economic concerns!

For example, if the temperature is 91°, it is dusk, the relative humidity is 40%, and heavy work is to be done, such as moving heavy materials with a wheelbarrow:

Start with 91° and add 3° because the humidity is 40% [91°+3°=94°]. Go to 94° in the table; under these conditions, it would be reasonable to follow a normal work schedule.

TABLE 1. APPROACH FOR SETTING WORK/REST SCHEDULES FOR WORKERS WEARING NORMAL WORK CLOTHING (light colored cotton) (not FRC’S)*

Adjusted Temperature* (calculated from table above)

Light

Intensity

Work

Moderate

Intensity

Work

Heavy

Intensity

Work

900 Normal Normal Normal
910 Normal Normal Normal
920 Normal Normal Normal
930 Normal Normal Normal
940 Normal Normal Normal
950 Normal Normal 45/152
960 Normal Normal 45/15
970 Normal Normal 40/20
980 Normal Normal 35/25
990 Normal Normal 35/25
1000 Normal 45/152 30/30
1010 Normal 40/20 30/30
1020 Normal 35/25 25/35
1030 Normal 30/30 20/40
1040 Normal 30/30 20/40
1050 Normal 25/35 15/45
1060 45/152 20/40 Caution3
1070 40/20 15/45 Caution3
1080 35/25 Caution3 Caution3
1090 30/30 Caution3 Caution3
1100 15/45 Caution3 Caution3
1110 Caution3 Caution3 Caution3
1120 Caution3 Caution3 Caution3

No adjusted temperature above 1120   = No work

10/50 = 10 minutes work and 50 minutes rest each hour danger!

15/45 = 15 minutes work and 45 minutes rest each hour

20/40 = 20 minutes work and 40 minutes rest each hour

25/35 = 25 minutes work and 35 minutes rest each hour

30/30 = 30 minutes work and 30 minutes rest each hour

335/25 = 35 minutes work and 25 minutes rest each hour

40/20 = 40 minutes work and 20 minutes rest each hour

45/15 = 45 minutes work and 15 minutes rest each hour

50/10 = 50 minutes work and 10 minutes rest each

normal schedule=  60 minutes of every hour

 

 

 

NOTES:

1 This table is based on American Conference of Governmental Industrial Hygienists limits for heat-acclimatized adults in effect at the time the document was published (1993).

Assumptions include physically fit, well-rested, and fully hydrated workers under the age of 40; adequate water intake; 30% relative humidity; natural ventilation with perceptible air movement; and air temperature readings in Fahrenheit, taken in the shade, no sunshine or no shadows visible.

2  45/15 minutes = 45 minutes work and 15 minutes rest during each hour.

3 Indicates very high levels of heat stress. Consider rescheduling activities for a time when the risk of heat illness is lower.

TABLE 2. APPROACH FOR SETTING WORK/REST SCHEDULES FOR WORKERS WEARING CHEMICAL-RESISTANT SUITS  OR LIKE AND KIND*

Air Tempera-ture

Work/Rest Schedules

–Light Work–

–Moderate Work–

–Heavy Work–

Full Sun Partly Cloudy No Sun1 Full Sun Partly Cloudy No Sun1 Full Sun Partly Cloudy No Sun1
75°F Normal Schedule Normal Schedule Normal Schedule Normal Schedule Normal Schedule Normal Schedule 35/253 Normal Schedule Normal Schedule
80°F 30/30 Normal Schedule Normal Schedule 20/40 Normal Schedule Normal Schedule 10/50 40/20 Normal Schedule
85°F 15/45 40/20 Normal Schedule 10/50 25/35 Normal Schedule Cautio4 15/45 40/20
90°F Caution4 15/45 40/20 Caution4 Caution4 25/35 Stop Work Caution4 15/45
95°F Stop Work Stop Work 15/45 Stop Work Stop Work Stop Work Stop Work Stop Work Stop Work

There is no entry over  95 0 work should have been stopped before the temperature reached  960

NOTES:

*This table is based on values for heat-acclimatized adult workers under the age of 40 who are physically fit, well-rested, and fully hydrated; with the assumptions of Tyvek coveralls, gloves, boots, and a respirator being worn; adequate water intake; and air temperature readings taken in the shade. Cooling vests may enable workers to work for longer periods. Adjustments must be made when additional protective gear is worn.

2 No shadows are visible or work is in the shade or at night.

10/50 = 10 minutes work and 50 minutes rest each hour danger!

15/45 = 15 minutes work and 45 minutes rest each hour

20/40 = 20 minutes work and 40 minutes rest each hour

25/35 = 25 minutes work and 35 minutes rest each hour

30/30 = 30 minutes work and 30 minutes rest each hour

335/25 = 35 minutes work and 25 minutes rest each hour

40/20 = 40 minutes work and 20 minutes rest each hour

45/15 = 45 minutes work and 15 minutes rest each hour

50/10 = 50 minutes work and 10 minutes rest each

normal schedule=  60 minutes of every hour

4 Indicates very high levels of heat stress. Consider rescheduling activities for a time when the risk of heat illness is lower.

SOURCE: Adapted from: U.S. EPA/OSHA. 1993. A guide to heat stress in agriculture. EPA-750-b-92-001

Other resources with approaches and tips for setting work/rest periods include:

OSHA’s Technical Manual Table III: 4-2 offers a simple chart showing several example WBGT meter readings and the appropriate work/rest schedules for light, moderate or heavy work.

The American Conference of Governmental Industrial Hygienists (ACGIH) describes a detailed method of determining work/rest schedules based on numerous factors including WBGT meter readings. The schedule can be adjusted for work demands and clothing type. This work/rest schedule method is published as: Heat Stress and Strain, in TLVs and BEIs, American Conference of Industrial Hygienists, Cincinnati, OH.

 

View KENNETH P MATTHEWS NCCER-CSST,CSSS, E.C.P INT. F.F&E.M.T.-b's profile on LinkedIn

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